Elizabeth Warren raised a whopping $42 million for her Senate race — more than any other congressional candidate in the country. Yet the noted scholar on the root causes of debt and bankruptcy made a surprising admission on Wednesday: she needs a little help paying her bills.

In an e-mail to supporters, the senator-elect from Massachusetts revealed that her campaign is in debt and asked for donations to help her out of the hole. Though she did not disclose the sum in her e-mail, a campaign official said Warren owes $400,000.

An aide declined to elaborate on other expenses that went over budget.

Warren had a massive campaign with 130 paid staff members and television ads on constant rotation.

“Everyone, we need a little more money to pay off our final bills,” Warren wrote. “Can you help one more time?”

It is not unusual for campaigns — even strong, well-funded campaigns — to end in debt.

Just last month, former President Bill Clinton sent a fund-raising e-mail asking for donations to help his wife, Hillary Clinton, retire the debt from her 2008 presidential campaign. Politico reported that Clinton still owed $73,000 as of Sept. 30.

Nevertheless, the disclosure that Warren owes money is notable because she raised such staggering sums in her race against Senator Scott Brown, shattering records month after month as she tapped into a vast network of loyal supporters across the country.

Warren is also considered a preeminent scholar on why families and businesses go broke. Her books include “All Your Worth,” a guide to managing household finances, and “As We Forgive Our Debtors,” a study of the American middle class.

The subject line of Warren’s e-mail — “I’ll come out and say it” — suggests that the Harvard Law professor, who plans to take a seat on the Senate Banking Committee, feels a bit sheepish about having to solicit even more cash from her supporters.

“Right now, I’d rather be writing about filibuster reform and banking regulation,” Warren wrote. “But we still have a little more to do to wrap things up. Can you help one more time to finish 2012 strong?”

Brown’s campaign, which raised about $30 million, said in an e-mail to the Globe on Wednesday that it has no debt. But Brown’s campaign manager, Jim Barnett, would not say how much cash the senator has left over if he chooses to run for office again.

Candidates often struggle to stay within budget, given the pressures they face to compete in the closing weeks of a race, said Steve Duprey, a Republican national committeeman from New Hampshire who served as finance chair for Senator Kelly Ayotte’s campaign in 2010.

“It’s just unusual that after raising that much, [Warren] would need to raise more to get rid of her debt,” Duprey said. “I hope she a does a better job balancing the federal budget than she did with her campaign books.”

Mo Elleithee, a Democratic strategist who was a spokesman for Hillary Clinton’s presidential campaign, said the senator-elect should not be faulted.

“In a race like that, it’s so competitive, and there’s so much you’re trying to accomplish, you want to spend every dime that comes in,” he said. “You can’t afford to leave anything on the table.”

If Warren were $1.5 million or $5 million in debt, there would be cause for concern about her financial management, Elleithee said.

“But for a $42 million campaign to go just barely over budget speaks to some pretty good management,” he said.

Given that Warren was able to raise $2.5 million in the first half of October alone, it may not take her long to close her $400,000 deficit.

That sum, after all, represents less than 1 percent of the $42 million she hauled in during the campaign. “It’s easy money,” Elleithee said.